feat: link to intrinsic npm diff

Closes #3304

lib/config/definitions.js

@@ -1011,6 +1011,10 @@ const options = [
       fileMatch: ['(^|/)package.json$'],
       rollbackPrs: true,
       versionScheme: 'npm',
+      prBodyDefinitions: {
+        Change:
+          '[{{#if displayFrom}}`{{{displayFrom}}}` -> {{else}}{{#if currentValue}}`{{{currentValue}}}` -> {{/if}}{{/if}}{{#if displayTo}}`{{{displayTo}}}`{{else}}`{{{newValue}}}`{{/if}}](https://diff.intrinsic.com/{{{depName}}}/{{{fromVersion}}}/{{{toVersion}}})',
+      },
     },
     mergeable: true,
   },